How do you change a desktop computer battery?

To change a desktop computer battery, first turn off the computer and unplug it from the power source. Open the computer case by removing screws or sliding off the side panel, depending on the model. Locate the CMOS battery on the motherboard, usually a round, silver coin-cell battery; carefully remove it and replace it with a new one, ensuring the correct orientation. Finally, close the case, plug the computer back in, and power it on.